PREFACE. 
The object of the present Catalogue is to give a com- 
plete list of all the genera and species of Geometrites known 
to exist in the different collections. The letters a , b , c, 
&c., after the species, denote the specimens now contained 
in the British Museum, followed by the habitat and the mode 
in which each of them was obtained, and the absence of 
these letters indicates the species which are desiderata, and 
therefore desirable to be procured for the collection. 
JOHN EDWARD GRAY. 
British Museum , 
March 1, 1860. 
